1. Field of the Invention
The present invention relates to a film layer and a method for semiconductor devices; more particularly, to a barrier layer and a fabrication method thereof.
2. Description of the Related Art
Complementary Metal Oxide Semiconductor (CMOS) technology has been frequently applied in manufacturing integrated circuits (IC). With the advance of CMOS technology, the miniaturization of CMOS devices according to a scaling rule is used in a semiconductor device to achieve large-scale integration and high-speed operation. In addition to the miniaturization of the scale of the CMOS devices, multiple-level interconnect technology is also applied to increase the high density of integration.
In multiple-level interconnect technology, a barrier layer usually is formed in a via or contact hole before deposition of a metal layer. The conformity of the barrier layer affects the subsequent deposition of the metal layer. In a worse case, a non-conformal barrier layer results in an overhead issue at the top of the via or contact hole. The overheads may cause a pin hole in the via or contact hole so that the metal layer cannot fill therein. The overhead issue becomes worse when the scale of the contact or via hole shrinks. Accordingly, the formation of a conformal barrier layer in a miniaturized via or contact hole is critical in semiconductor manufacturing.
U.S. Pat. No. 6,402,907 shows a method of forming a barrier layer in a high aspect ratio recess in a dielectric layer on a semiconductor wafer. The method includes two main steps: (a) sputtering, at a pressure of 1 mTorr or less, a titanium layer onto an exposed surface of the recesses with the dielectric layer at a first distance from a sputter source or target; and (b) sputtering at a pressure in the range 1 millitorr to 0.5 millitorr a stochiometric titanium nitride layer onto the titanium layer with the dielectric at a second shorter distance from the sputter source or target.
U.S. Patent Publication No. 2003/0042133 shows a method for forming a barrier layer in a via or contact hole. The method first applies a first pressure in the chamber during an increase in pressure which is different from a second pressure in the chamber during a decrease in pressure, while an equal amount of the nitrogen gas is provided into the sputter chamber. Accelerated particles collide with the target to sputter the metal material from the target.